Retigabine (N-[2-amino-4-(4-fluorobenzylamino)phenyl]carbamic acid, ethyl ester] (U.S. Pat. No. 5,384,330) has been found to be an effective treatment of seizure disorders in children. Bialer, M. et al., Epilepsy Research 1999, 34, 1-41. Retigabine has also been found to be useful in treating pain, including neuropathic pain. Blackburn-Munro and Jensen, Eur. J. Pharmacol. 2003, 460, 109-116; Wickenden, A. D. et al., Expert Opin. Ther. Patents 2004 14-(4).
A form of epilepsy known as “benign familial neonatal convulsions” has been associated with mutations in the KCNQ2/3 channels. Biervert, C. et al., Science 1998, 27, 403-06; Singh, N. A. et al., Nat. Genet. 1998, 18, 25-29; Charlier, C. et al., Nat. Genet. 1998, 18, 53-55, Rogawski, Trends in Neurosciences 2000, 23, 393-398. Subsequent investigations have established that the primary site of retigabine action is the KCNQ2/3 channel. Wickenden, A. D. et al., Mol. Pharmacol. 2000, 58, 591-600; Main, M. J. et al., Mol. Pharmcol. 2000, 58, 253-62. Retigabine has been shown to increase the conductance of the channels at the resting membrane potential and to bind the activation gate of the KCNQ 2/3 channel. Wuttke, T. V. et al., Mol. Pharmacol. 2005, 67, 1009-1017. With increased sophistication of research in this area, retigabine has also been shown to increase neuronal M currents and to increase the channel open probability of KCNQ 2/3 channels. Delmas, P. and Brown, D. A. Nat. Revs Neurosci., vol. 6, 2005, 850-62; Tatulian, L. and Brown, D. A., J. Physiol., (2003) 549, 57-63.
The recognition of retigabine as a potassium channel modulator has prompted numerous searches for other potassium channel modulators among compounds with various structural features in common with retigabine.